Title: UV-LIGA interferometer biosensor based on the SU-8 optical waveguide
Authors: Shew, BY
Kuo, CH
Huang, YC
Tsai, YH
Department of Mechanical Engineering
Keywords: optical waveguide;interferometer;biochemical sensor;SU-8 resist;LIGA process
Issue Date: 17-May-2005
Abstract: SU-8 resist was used as a core/cladding waveguide material to fabricate a Mach-Zehnder interferometer (MZI) for biochemical sensing. The refractive index of the SU-8 resist was fine-tuned with a Delta n of 0.004 for single-mode transmission. The UV lithography processes of the SU-8 resist were also optimized to pattern the high resolution (1 mu m) and high aspect ratio (A(R) = 6) Y-branch structure of the optical interferometer. Optical measurements reveal that the SU-8 MZI chip can efficiently transmit the NIR laser (lambda = 13 10 mu) with a total loss less than 6 dB. When one branch of the MZI is in contact with the analyte, the interfered intensity stabilizes after the soaking time exceeds 5 min. NaCl solution with a concentration of 10(-9) g/l can be detected using the SU-8 MZI chip. In the future, the polymer MZI chip can be mass-produced by molding process (or the LIGA process). The low-cost, label-free, real-time and high-sensitivity MZI chip will benefit many applications related to biological, environmental and industrial detection. (c) 2005 Elsevier B.V. All rights reserved.
URI: http://dx.doi.org/10.1016/j.sna.2005.01.004
ISSN: 0924-4247
DOI: 10.1016/j.sna.2005.01.004
Volume: 120
Issue: 2
Begin Page: 383
End Page: 389
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